Patent GB-1265347-A (GB)
IPC: D01D5/30
Filed: 1969-11-13
Abstract: 1,265,347. Composite filaments. KANEGAFUCHI BOSEKI K.K. 13 Nov., 1969 [13 Nov., 1968; 31 July, 1969 (3)], No. 55751/69. Heading B5B. A composite multi-segment filament, which may be of non-circular especially trilobal crosssection, comprises at least 10 fine segments formed of a fibre-forming linear polyamide and/ or polyester which extend substantially continuously along the filament and occupy at least a part of the periphery of the filament, the segments being of irregular cross-section and differing from each other in the shape and area of their cross-sections and adjacent segments having an average space therebetween of at least 0À1 Á, at least at the periphery of the filament. The segments, which may be of generally flat cross-section may be bonded to one another by a fibre-forming linear polyester or polyamide. Suitably from 10 to 100, or from 100 to 10,000 segments may be present, the average space between adjacent segments being from 0À1 to 1 Á, and the average cross-sectional diameter being from 0À1 to 10 Á. The whole of the filament may consist of the fine segments or the filament may consist of the finely segmented component and a homogeneous component which is a single fibre-forming polymer, e.g. a polyamide or polyester, the two components being bonded together and extending continuously along the length of the filament; the segmented component may surround the homogeneous component, (i.e. sheath-core structure) or the two may be in side-by-side relationship. At least five, and preferably at least twenty, ends of the segments may be exposed at the surface of the filament, and segments forming the periphery of the filament, or all the segments, may be fibrillated (Fig. 27). Desirably, the segments consist of polyamide (especially nylon-6 or nylon-66) and polyester (especially polyethylene terephthalate or polyethylene oxybenzoate) in a ratio of 1 : 10 to 10 : 1, especially 1 : 3 to 3 : 1. Such filaments are made by treating a composite filament formed of a polyamide and polyester and having a layer-multiplied, grainy, nebular or archipelagic cross-sectional structure, with an acid or an alkali to remove a part of the polyamide or polyester. At least 3%, preferably 10-50%, of polyamide or polyester based on the layermultiplied component may thus be removed. Acids specified include acetic, formic, hydrochloric, nitric, phosphoric and sulphuric acids and alkalis specified include lithium, potassium and sodium hydroxides, and sodium carbonate. Composite filaments having the specified structure may be made by layer-multiplying a molten polyamide and polyester by joining- dividing steps in different phase to give the required number of segments into a grainy nebular or archipelagic segment structure and spinning the layer-multiplied polymers through spinneret orifices to form composite filaments. A distorted grainy cross-section may be achieved in this way, having at least 20 segment ends at a distance of less than 5-10% of the filamentary diameter from the filament surface. Such starting filaments are disclosed in British Specification 1,192,270. A layer-multiplied component may be extruded simultaneously with a homogeneous component consisting of a single fibre-forming polymer, to form a filament having the cross-section shown in Figs. 14, 15 or 16.  Joining and dividing may be effected using a network/passage type layer-multiplier, or a layer-multiplying mixer in which reservoirs and passages are combined, may be used to form the archipelagic or nebular segment structure. Such mixers are disclosed in Specifications 1,229,841 and 1,192,270.  Filaments of various cross-sectional structures useful in the production of the filaments of the invention are shown also in Figs. 13 (trilobal grainy), 22 (trilobal nebular), 23, 24 and 25 layer-multiplied archipelagic or nebular having a portion composed of a single fibre-forming component. Treatment with acid or alkali leads to the development of ridges or fibrils, so that the structure of the final filament (Fig. 27) resembles a natural fibre; the filaments may also show a high gloss.